Geological Survey of Finland, Special Paper 46 - arkisto.gsf.fi

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Geological Survey of Finland, Special Paper 46 Richard Gyllencreutz, Jan Mangerud, John-Inge Svendsen and Øystein Lohne The timing and pattern of the deglaciation of the Eurasian Ice Sheet is of key importance for Late Quaternary environments, on a local and global scale. The increasing resolution of glacier and climate models demands detailed information about the deglaciation on a calendar-year time scale. This is the rationale for the ongoing project DATED, whose goal is to serve as a primary source of information about the ice growth towards LGM and the deglaciation of Eurasia by presenting digital maps of ice growth and decay, and a database of published dates ( 14 C, OSL, TL, cosmogenic exposure, clayvarve), end moraines, and other relevant features. Large volumes of data on the Eurasian deglaciation pattern and chronology exist in the literature, but most investigations provide information only on the local or regional level. Therefore, it is diffi cult to make wide ice-sheet syntheses, as interpretations between areas differ, and much of the relevant information is published in local journals, maps, and theses. Previous large scale reconstructions of the entire Eurasian Ice Sheet or its major constituents (e.g. Andersen 1981, Lundqvist & Saarnisto 1995, Kleman et al. 1997, Boulton et al. 2001, Svendsen et al. 2004) have the disadvantage of not being fully transparent to their data sources. These reconstructions are therefore diffi cult to validate and refi ne by further investigations. Recently, large efforts have been made to overcome these problems by creating digital maps connected to relational databases, where the information can be traced back to its original source. The GIS maps produced by Ehlers and Gibbard (2004) shows a compilation of glacial morphological features from the entire Eurasian Ice Sheet, but the level and amount of information varies widely between the contributing countries, 114 INTRODUCTION and chronologic information is only available as sparse, interpreted ages of certain features, often without reference to the original dates. The BRIT- ICE-project (Clark et al. 2004, Evans et al. 2005) produced a freely available GIS with detailed information about glacial features related to the last British (Devensian) Ice Sheet, with full sourcetransparency. The BRITICE database, however, does not include chronologic data, partly because of the very limited number of available dates (Clark et al. 2004). The success of the BRITICE project was a major inspiration for creating the ice-sheet wide DATED database, where all available morphologic as well as chronologic information is collected. The main purpose of DATED is to serve as an updated source of interpreted ice margins and dates for the deglaciation of the Eurasian Ice Sheet, to provide accurate digital maps with calendar-year isochrones to modelers and other researchers. It will also show where data is lacking, and facilitate reinterpretation of the deglaciation pattern. The present paper is a project description of work in progress. The fi rst version of DATED will be published and made available on the internet in 2007, in a format readable for ordinary web-browsers. Information about DATED can be found on the web site http://www.gyllencreutz.se. This task is a part of the British-Dutch-Norwegian co-operative project Ocean Reconstruction and Modelling of the European deglaciation (ORMEN, http://www. bridge.bris.ac.uk/projects/ORMEN/Index.html) led by Sandy Harrison, University of Bristol, and is also part of the project Ice Age Development and Human Settlement in northern Eurasia (ICEHUS), led by John Inge Svendsen, University of Bergen.
The area comprised in DATED includes all areas covered by the northwest Eurasian (Scandinavian-, British-Irish-, and Barents-Kara-) ice sheets (Fig. 1), that is part of or the entire following countries: Ireland, Great Britain, Denmark, Norway, Swe- STUDY AREA den, Finland, Germany, Poland, Ukraine, Belarus, Lithuania, Latvia, Estonia, Russia, the Arctic areas between 0° E and 110° E, as well as the surrounding sea areas. Fig. 1. Geographical extension of DATED, which is approximately within the asynchronous LGM reconstruction by Svendsen et al. (2004) (white line). Elevation data from the SRTM30PLUS dataset (Becker & Sandwell 2006). Database (DATED 1) The database is created and maintained using Microsoft Access®. The goal of the database is to cover all available dates of the Eurasian deglaciation, based on radiocarbon ( 14 C), optically stimulated luminescence (OSL), thermoluminescence (TL), cosmogenic exposure (e.g. 10 Be, 36 Cl), and clayvarve records. The database will include ice growth towards the LGM, and therefore start with dates of the Ålesund Interstadial, c. 35-38 cal kyr BP (Mangerud et al. 2003). Dates showing the vertical extent of the ice sheet will also be included (e.g. Linge et al. 2006, Ballantyne et al. 1998). Geological Survey of Finland, Special Paper 46 DATED – A GIS-based Reconstruction and dating Database of the Eurasian Deglaciation METHODS The dates in the database are collected from published scientifi c papers of various kinds (original research articles, reviews and syntheses, map descriptions, or PhD-theses). When necessary, additional metadata (e.g. map coordinates and sediment descriptions) are acquired using the unique laboratory codes, for example, from published 14 C-laboratory reports (e.g. Håkansson 1982) or directly from the author. All entries or changes to the database are performed by the authors of this paper to secure the data integrity and quality control. Researchers who wish to contribute with data or otherwise comment 115
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GEOLOGICAL SURVEY OF FINLAND Specia
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Johansson, P. & Sarala, P. (eds.) 2
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4 CONTENTS Preface, Peter Johansson
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Geological Survey of Finland, Speci
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Applied Quaternary research in the
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DRUMLINS IN KUUSAMO AND RANUA In Ko
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RIBBED MORAINES IN SOUTHERN FINNISH
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ued fl owing from west to east but
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Sarala, P. 2005a. Glacial morpholog
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Pleistocene deposits in southern Li
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Heavy minerals Medininkai Upland Ei
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The South Lithuanian phase of glaci
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Fig. 4. Lateral drainage channels o
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for dating. The deglaciation of nor
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In Lokka, the sheetfl ow tracks wer
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Fig. 5. A compilation of low altitu
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